Structural and photoluminescence properties of a trivalent rare earth Sm ion-doped PVA/PVP blend polymer films

Abstract

Transparent polyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP) and various concentrations of Sm3+ ion-doped PVA/PVP blend-polymer films were prepared using the solution cast method. The structural properties were studied by using XRD and FTIR. Optical UV-Vis, photoluminescence, and decay studies were carried out for prepared PVA/PVP blend polymer films. The XRD confirms the structural change in PVA/PVP blend-polymer with the doping of Sm3+ ion. From FTIR, Sm3+ ion forms the complex formation within the PVA/PVP polymer structure. The allowed band gap decreased from 5 to 4.6 eV, and the refractive index increased from 2.4 to 2.45, increasing Sm3+ ion concentration. From the energy band gap, the bonding parameters ( and δ) were calculated to find the covalent/ionic bond nature of the prepared polymer films. The emission spectra were measured for Sm3+: PVA/PVP with the excitation of 402 nm wavelength (6H5/2→4F7/2). 4G5/2→ 6H7/2 shows maximum intensity at 0.4 wt % of Sm3+, and beyond concentration, quenching was noticed. It is observed from the decay curve that the lifetime of PVA/PVP samples doped with Sm3+ at all concentrations decreases with the increase of Sm3+ ion concentration. It was noticed from CIE chromaticity that Sm3+: PVA/PVP blend polymer films are more appropriate for enhancing reddish-orange photonic emission. Based on the above results, Sm3+: PVA/PVP blend polymer films are suitable for reddish-orange luminescent applications.